Circuit interrupter



Patented Feb. 16, 1954 CIRCUIT INTERRUPTER Alert M. Opsahl, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 5, 1950, Serial No. 177,826

16 Claims.

This invention relates to circuit interrupters in general, and, more particularly, to improved arc-extinguishing structures for circuit interrupters in general, and more particularly to circuit interrupters of the automatic reclosinzg type.

The general object of my invention is to provide an improved, more effective arc-extinguishing structure for a circuit interrupter in which the insulation strength between the stationary contacts, when the interrupter is in the open position, is greatly increased, so as to minimize the possibility of progressive breakdown between the contacts, and also to enable the interrupter to be applied to higher voltage ratings.

When substantially enclosed arc-extinguishing chambers are utilized in circuit interrupters, particularly of the oil-break type, and in a construction wherein a substantially horizontal insulating surface is positioned between the stationary contacts, there is the hazard or" carbon and contaminated conducting particles collectingr upon the horizontal surface extending between the pair of stationary contacts and thereby giving rise to the danger of progressive insulation breakdown between the contacts when the interrupter is in the open circuit position. lt is a more particular object of my invention to provide an improved arc-extingushing structure which will greatly minimize or entirely eliminate, such a possiblity of progressive breakdown between the stationary contacts in a circuit interrupter of the foregoing type.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawing in which:

Figure 1 is a vertical sectional view of an embodiment of my invention as applied to a reclosing type of circuit interrupter, the contact structure being shown in the closed circuit position;

Figure 2 is a side elevational View of only the arc-extinguishing chamber of Figure 1, taken substantially along the line II-II cf Figure l; and

Figure 3 is a sectional view taken along the line III- III of Figure 2, looking in the direction of the arrows.

The invention is illustrated in the drawing as being embodied in one form of automatic reclosing circuit breaker, with the particular breaker herein illustrated being more particularly described and claimed in the copending patent application, Serial No. 8,044, liled Februvary 13, 1948, entitled Circuit Interrupters, by James M. Wallace and Andrew W. Edwards, and

assigned to the same assignee as the instant application.

The circuit breaker is mounted in a metal tank 2 having a closed bottom wall and an open top and adapted to be filled with a liquid up to the level L, preferably an arc-extinguishing liquid such as oil or the like. Preferably, the tank is lined at least over the bottom wall and up to a point adjacent the open top of the container with a liner 3 of insulating material such as fiber, or the like. The upper end of tank 2 is provided With an outwardly extending flange i on which the iiange 8 of a cover casting t is adapted to be seated preferably, with a gasket IB interposed therebetween. Flange 8 of cover casting t may be provided with an integral lip I2, and the cover may be secured to the tank in any desired manner, such for example, as by bolts (not shown) extending through openings in cover flange 8 and secured to suitably formed brackets on the tank.

The breaker contacts, arc-extinguishing structure, and the contact-actuating mechanism are all adapted to be supported in tank 2 from cover casting 6 by means of a plurality of integral supporting lugs I6 (only one of which is shown) depending from the top wall of the cover casting and adapted to engage spacer sleeves i8 of insulating material suitably secured to supporting lugs I6 and to a supporting casting 25. A supporting plate 22 may be supported from casting 20, so that a solenoid coil 24 may be mounted between casting 20 and supporting plate 22, with the central opening in the coil aligned with openings provided in casting 2t and plate 22. Supporting casting 20 and supporting plate 22, together with the bolts (not shown) securing them together, are of a, magnetic material, such as iron or the like, to complete a magnetic circuit of low reluctance outside of solenoid coil 2li, which terminates at opposite ends of the central opening through the coil in which the working air gap of the coil is located.

spaced stationary contacts 25 of the breaker are supported within an insulating tube 2x3 at the lower end thereof, and on opposite sides of the tube, respectively. Tube 28, which may be of any desired insulating material, such as ber, or the like, is supported at its upper end from plate 22 by supporting brackets 3S, which are welded or otherwise secured to plate 22, and have screws for securing tube 28 thereto, with the upper end of tube 28 being closely adjacent to, but spaced from, plate 22. Stationary contacts 2t are each mounted on its own supporting bracket 32, with each bracket having a U-shaped portion for receiving the lower edge of the tube 23 and being secured thereto, as by a bolt Bil. Tube 28 has opposed vent openings 35 in opposite sides, located directly above stationary contacts 25, respectively, for a purpose to be described.

When movable bridging contact 3% is moved upwardly to interrupt the circuit, two arcs, which are in series, will 'be drawn to stationary contacts 2S, respectively. These two arcs Ycreate considerable pressure inside tube 23. of the close spacing of the upper end of tube 2S in regard to supporting plate 22?,l of the order of le inch, there will be relatively little 'ow of oil out the top of the tube, so that therewill be a substantial quantity of fluid forced out the two vent openings 35 in a direction transversely of the arcs drawn across these vent openings, so as to provide a flow of fresh oil through these arcs to extinguish them at 'a current zero. As soon as the arcs are extinguished, there will be a quantity of gas present Within tube 28; and, in instances where the contacts are recl'osed vwithout time delay, this gas must be rapidly removed from tube 28 in order to restore the dielectric strength v-Jithin the tube and provide oil for subsequent interruption. While the close spacing of the upper end of tube 28 and supporting plate 22 restricts the outilow of liquid from the tube, it furnishes relatively free venting for gas, which vent is open at all times. Moreover, the space within tube 2S is immediately filled with fresh oil, which may ow unobstructedly onto the lower end of tube 28 due to the head of liquid in tank 2. Accordingly, in addition to providing a simpl-ined structure which provides a transverse ilow of fresh arc-extinguishing liquid to quick-ly deionize the arcs when the circuit breaker opens, the structure described above provides extremely fast ilushing of the are chamber, which is of especial importance in this type of circuit breaker which may have one or more circuit-opening and closing yoperations which are not delayed, but occur substantially instantaneously.

The upper end of contact-actuating rod et has con ecting links :lil pivotecl thereon, as by :a pivot pin te, with the upper ends of vthese connecting links mounted on a common pivot pin 58 for a pair of toggle levers 52 and lill. 'Toggle levers 52 and l! are both formed of sheet material, with lever 55 being bent to substantially channel .form with outwardly extending flanges 55 adapted to be received at the free ends thereof in ecesses 58 provided in the spaced downwardly d fingers of an angled supporting bracket Se which, in turn, is secured (as by a screw et) to a lug integral with the -cover casting. A coil tension spring 58 has one end hooked into rvan opening provided in toggle lever 52, and has the opposite end thereof hooked over an integral spring support on the cover casting. Toggle lever 52 has an integral hook portion 55 passing through an opening in lever 5d to limit Aseparation of the levers.

It will be observed that in the Aclosed cir uit position of the breaker, lustrated on the drawing, the line of action of toggle spring $53 is below the pivot supporting recesses 53 for toggle lever 5G, and, accordingly, the toggle spring acts to bias bridging contact 35 into engagement with sto.- tionary contacts 2S of the breaker, under a prodetermined pressure. However, as soon c'cntact-operating rod le moves upwardly to separate the 'bridging contact from the fixed contacts of the breaker, toggle lever Eil will Vpivot 'about Because recesses 53, and the line of action of toggle spring R58 will thus be caused to approach that pivot point so that in response to a very small contact separation, the line of action of toggle spring 58 will pass through pivot recesses 5s, which is the ori-center position of the resilient toggle arrangement comprising toggle levers 52 and 54 and toggle spring SS. Asia practical matter, the opening movement of the contacts necessary to move toggle levers 52 and 513 to the on-center position mentioned above may be made very small, in one actual device being of the order of onequarterrof an inch. When toggle levers 52 and Ell reach their on-center position referred to above, further relative movement of the two toggle levers in the same direction is prevented because the upper edge oi toggle lever 52 engages the base of the central channel formation of toggle lever 5t. Moreover, since the point at which toggle spring fit is hooked into lever 52 then substantialliT coincides with recesses y58 in which toggle lever ed pivots contacteopen-- ing movement, it will be apparent that the Irernainder and major part of contact-opening movement will occur substantially uni-niuenc'e-ll by toggle spring Se.

Substantially the reverse of the above operiation occurs when contact-operating rod lll ymoves downwardly to close the circuit from the fullopen contact position, because dur-ing the first and major part of contact-closing movement, levers 52 and lill will be in engagement 'so that such movement will be uniniiuenced by toggle spring 68. However, as soon as pivot 5! passes below a line drawn from the remote end of toggle spring 63 through pivot recesses es for link Ski, toggle spring ed will then be 'eiective to move the toggle levers toward the full-line position shown in Fig. l, andthe force exerted by 'toggle spring et thus tending to close the contacts will continue to increase as toggle levers 512 `and 5'4 move further away from their ori-center positions.

Solenoid coil ?Jl, previously mentioned, is adapted to be energized under certainconditions for automatically opening the circuit breaker contacts. The central opening through coil 24 preferably is provided with a 'cylindrical sleeve lll in which a solenoid core lill is adapted to be slidably mounted in a piston-like manner. A fiat washer lil, which may be of insulating material, is secured to contact rod lil immediately above bridging contact ile, as by a split securing ring Se, mounted in a groove formed on rod M; and core it has an enlarged piston flange "231 at the lower end thereof having a ilat annular end surface adapted to seat on washer i8 at the normal position of the parts illustrated on the 'drawing. t will be observed that solenoid coil 24 is spaced from supporting plate 22 .by the apertured flange 3d of a sleeve i9, which is received 'in the lower end of dashpot cylinder sleeve 751. Depending from flange Sil of sleeve i9 is a cylindrical skirt 85, which extends through the opening in supporting plate 272, about Acore T6, -an'd into tube 2g. The purposes and operation of these structures will be hereinafter described.

A contact-actuating sleeve 132 is telescoped @over contact-actuating rod de, and its 4lower Vend Ais received in core "i6 preferably being threadably mounted therein. A coil compression spring t5 provided within actuating sleeve '812 Ion contact- .actuating rod lill, and vit is adapted `to lreact between core 16 anda 'collar secured to actuated in the top wall of cover casting 6. The circuit proceeds by conductor 98 directly to one fixed contact 26 of the breaker. When the contacts are in engagement, the circuit then proceeds through bridging contact 36 to the other fixed contact 26, and then by Way of a conductor |00 `to one terminal of solenoid coil 24. The other terminal of coil 24 is adapted to be connected by a conductor |02 to the conducting means in the other terminal bushing 90. It will be apparent that solenoid coil 24 is connected in series in the circuit through the circuit breaker so as to be energized at all times an amount dependent upon the value of the load current owing in the circuit.

For any given rating of circuit breaker, solenoid coil 24 is designed to become suiciently energized, when the load current in the circuit exceeds its rating, as to attract core '|6, and move it upwardly within sleeve 14. Assuming the upper end of sleeve 14 to be closed so uid cannot escape, core 'I6 will move upwardly, retarded by the necessity for displacing the liquid in sleeve 'I4 above the core through the relatively small clearance between the core 'I6 and sleeve 19 and between core 62 and casting 20. Accordingly, opening movement of the core will be slowed up by the aforesaid dashpot action an amount determined by the current value of the overload, and, therefore, an inverse time-current characteristic on opening is obtained. As core 'I6 commences its upward travel, bridging contact 36 being held engaged by toggle spring 68 does not move, so that spring 86 is compressed until the upward force of the spring 86 is sumcient to overcome the force exerted by toggle spring 68, at which time contact-actuating rod 44 will start to move upwardly. As soon as actuating rod 44 moves upwardly, the force exerted by toggle spring 68 begins to decrease, and, in a very short distance, has substantially no value at all, so that the remaining major part of the circuit-opening movement of bridging contact 36 occurs extremely rapidly due to expansion of spring 85. Flange 89 is provided on rod 44 to obtain a positive contact separation in the event there is any sticking or welding of the bridging contact to stationary contacts 26, by engagement therewith of a shouldered sleeve 83 mounted in the upper end of actuating sleeve 82. In either case, it is apparent that toggle levers 52 and 54 will be moved to their on-center position in the manner previously described, and bridging contact 36 will be moved by spring 86 to its full-open circuit position.

When the breaker contacts have attained their full-open circuit position, the parts associated therewith are biased to return by gravity. This closing bias is relatively light, and will be opposed by the dashpot action of core 16. Accordingly, the return movement will be relatively slow until pivot point 50 moves below the line of action of toggle spring 68 when toggle levers 52 and 54 are in engagement, whereupon bridging contact 36 will be rapidly moved to effect a snapaction closing of the breaker contacts by toggle spring 68. It will be observed that during circuit-closing movement of dashpot core 16, the dashpot action is due to the necessity of supplying liquid to the upper end of the dashpot through the relatively small clearance between core 16 and sleeve '19, core 82 and casting 2t. As previously explained, gases are generated during a circuit-interrupting operation in tube 28, and are vented from the upper end ci the tube. In order that such gases do not nd their way up through skirt on sleeve I9 into the dashpot space, especially during the rst part of a circuit-closing operation, when there may be a transient pressure condition within container 2 due to the preceding circuit-interrupting operation, the vents in flange 84 of sleeve 19 are provided, so that the intake at the lower end of dashpot sleeve 'i4 is located above supporting plate 22, and, consequently, at a point where any gases present within tube 26 cannot enter the dashpot space.

In order to provide for maintaining the breaker contacts separated, and to also provide for manual operation, spring means are provided for holding the breaker contacts open in response to the occurrence of a predetermined number of closely succeeding circuit-interrupting operations, which means can be manually actuated. This means comprises a toggle lever |04 having a slot |06 at one end thereof for receiving a pin |08 mounted between spaced supporting arms ||0 integral with cover casting 6. The other end |43 of the toggle lever |04 is pivoted, as by a pivot pin ||2, to the adjacent end of a second toggle lever ||4, and this, in turn, is mounted on a pivot pin I6 intermediate its ends on cover casting 6. A slot |20 is provided through the cover casting 6 for receiving the other end of toggle lever ||4 which acts as a manual operating handle at the exterior of the circuit breaker casing, being provided with a hook eye |22 in its outer end. A coil compression spring |24 is mounted on toggle lever |04 and reacts between washers mounted on the toggle lever, one of which engages supporting pin |86, and the other of which engages a shoulder located adjacent pivot ||2. Normally, toggle levers |04 and ||4 are held with pivot I2 below the centerline connecting pins |88 and H6, with the outer end of lever ||4 positioned in, and beneath, an integral hood |26 on cover casting 6, in engagement with an adjustable stop screw |28 mounted in the hood.

In the position of toggle levers |04 and ||4 illustrated, they have no eiiect on operation of the circuit breaker, as previously described, being normally inactive in this respect. However, the common pivot pin ||2 of toggle levers |64 and |4 is extended at one side toward toggle levers 52 and 54, and in the normal position of the parts extends beneath the adjacent flange 56 of toggle lever 54. Accordingly, if it is desired to manually open the circuit breaker contacts, a hook stick, or similar operating member, may be inserted in hook eye |22 of toggle lever ||4 and pulled downwardly to rotate the toggle lever in a counterclockwise direction about its supporting pivot Il?, to move toggle levers l|01| and |4 overcenter in an upward direction; and in doing this, the common pivot pin ||2 engages the adjacent flange 56 of toggle lever 54, and moves it upwardly in a counterclockwise direction, thus carrying contact-actuating rod 44 with it to separate bridging contact 36 from @gestaan 7 :stationary .contacts 125. "The contacts will'befhel open 'by fspring l 2i! :which fmaintainsztogg'l'e llevers lll and Mii in their upper overcenter position. With the breaker contacts :maintained at "their yopen `circuit position Ifollowing .the manual oir. 4cuit-opening operation .described above, .Ei-t will be apparent `that the router end .of toggle lever llld projects below hood i126 :of .cover :casting ii, :so .as to provide :fa readily :visible indication @that the breakercontacts are maintained at .1an fopen #circuit position. It will #further vIbe :apparent that .the breaker contacts may then abe closed only by .manual `operation of toggle 'lever .M24 'Lin the :opposite sdirection, that is, Aby exerting .Lan upward Aforcelon .thewouter :enduoie the togglelever to lrotate 4it in .a clockwise adirection, 'to move `it and itoggleiever Imi back iovercenter to the iulllline position illustrated on the drawing. ".flhi's 'manual :operation :of 'toggle lever HIM does not directly 1close Y:the breaker zc'onta'cts, ibut merely permits lclosure .of .the .contacts in ithe manner previously described, that is, initiahclosingmove- :ment of lthe 'contacts being .due "to ythe bias of gravity, :until llbridging contact i256 is closely :ad-

j-'acentsta'tionary contacts 22e, when toggle :spring f is rmoved below lits :ou-center position :and Lsuddenly becomes .effective lto fnally move the -contacts into engagement rapidly.

vAn l,integrating Ymechanism 'for automatically imoving 'toggle levers fi-iiand 'SM upwardly overcenter., .and thus preventing reclosure of .the acircuit breaker only in .response to :a l.predeter- `:mined number of closely .successive .circuit-in- J:terrupting operations, ani'at the same Ltime, for

kEautontlatically:controlling .the circuit-:openingand :closing .times in .a :predetermined :manner in :any .sequence Iof ,a plurality of closely successi-ve :oir- .cuit-.opening operations is provided, :comprising :.a cylindrical l'tube 13e secured in 'casting .20; zand this rtube .has a plug y|132 threaded into the lower .enti thereof, 4with 'thezplug having-,a small l,central opening controlled by :a ,ball-check "valve i514, which permits :new vof iuid into :the 'lower :end .of tube ite, :but prevents outflow. An integrat- .ing `piston lie 'is .mounted in cylindrical itube 23B r.and',norrnally rests .on the upperzend of iplug .The upper Yend .of piston .L35 :is provided 'with :a reduced extension .tell .at 'the upper @end thereof, having .a plurality -.o:E .spaced :circular .'iainges i @o .forming .rack teethithereon, anrlhav- .ing .an elongated ,extension i412 Ion the extreme zouter .end thereof, which positioned. below Lan "extension 'Eli-ii .on .toggle lever ille. :pawl ,lever its is pivotally mounted. at one end, as at :m5, this end .oi pawl lever his being :split .with legs 'located vat feach 'side of tube :E39 :and :with .pivot Mii Ksupported V.Crispanod supporting iianges 4Htl integral with :casting rZil. Eawllever lil-.li Suasa connecting web .intermediate its ends,:and,at1the .other end 'thereof the fsia'es of :the letter are -fex- :tended.outwardlygandlaterally, as at .4:53, tonormally bein .engagement with a washer Iiilzmount- `eci on sleeve i313 .in engagement with `anex'tenior shoulder on .this ltube. .Pawl lever HM `is .normaiiy :biased .into .engagement 'with washer @teil 'by -a coil rtension 'spring liet' hooked :over `une *remote edge of the web fof lthe pawlilever atene end, and anchored to an -earintegra'l withcast- Ling "20 at its other end. :"Pawl 1lever "Ieri -is `vvprovided with a v4pawl member +515 fpivotedithereon,

' mocked .off by piston glee.

fof dzhe circuit :breaker .contacts to provide for diierent openingclos'ing times on predeter-r .mined :circuit-,opening :and closing operations in any sequence l:of .closely successive operations, on continuing over-loads, the dashpot .formed Eby .sleeve 'ifi Jandsolenoidicore le has avent :I at .the upper Aend thereof, which is :annular in form heingaprovidedrincastng 2t about actuating sleeve :2.2. Annula-r vent :Lie "communicates withfa 4laterallyfextendingpassage 'llalso formed 'in casting-213,30 fthat fluid may escape from the upper en-d of sleeve ifi V` through annular vent i'l' zand passa-ge ii lai, and Vthen through-a pai-r of f .opposed operxings .H8 in tube |353, from whenceit may :escape through a discharge opening 1&9, valso .iormedzrn casting .2.0. rThe openings iS iin 5integrator tube le@ vare @aligned with 'passage ile Vand discharge fopening 130.

- 'With the parts fof the circuit .breaker fat rtheir ynormal positions., illustrated ,in Fig. 1,;it willbe apparent that when ,the circuit breaker-operates to :open the circuit, :the upper end of v-,dashpot ssleeve ifibeing open through annular 'vent Alle, `passage IP, openings i'iand-dischargeopening 30, solenoidzcere it ywillbefniovefupwardly very rapidlmsince the-liquid-in dashpot sleeve fili above theffcore :may be -freely vented through lthe -vent passages :mentioned above; and, consequently, Athe 'initial `circuit-opening -.operation of the :breaker :occur substantially instantaneously. ,Durf-ingesueh an .initial fast circuit epernng operation, .it will .be apparent that Contact rod. M and the jpants which move "with this roel will be moving at ffalhigh speed ano 'will have considerable :nio- .fmentunr .At :the end -of circuitopening .movement of the .contact rod 44' )and its associated parts, washer yon the rod approaches the flat surface at 'the lower end of core l' :formed -on enlarged piston ,iiange 8i, `and .a braking action .obtainededue to the necessity of forcingall liquid from between -these 4hat surfaces.

.As solenoid l@core IEB `moves upwardly on .such .circuit-opening operation, washer eiiil `will `be carried upwardly wthfac'tuating-sleeve .B2 .and .thus carry lthe vfree end. 01 pawl lever Me iupwardly .withiit zto .move :pawl .member i254 .into :engagement with the .upper Ione of flanges ist .on .integrating piston let, and -carry ,the ,piston upwardly .a ,predetermined kdistance Vthroughout topening,maniement oi sleeve. .Integrating .pis- `ton 4i375 is not, however, .carried upwardly a dis- .tance sufficient ,to ventirely remove reduced .por- .ton .L38 thereof from between openings ll .in cylinder li311, so that the .vent `.passa-geway from 'the -upper end of rlashpo't cylinder lili will Jnot 'be When .the breaker recloses following .such a .first -ast circuit-interrupting operation, suchreclosure will .also .occur extremely rapidly because 'core "iii not have .any dashpot action fin fits dashpot .sleeve '1.4 Clue ,to .the upper ventfor sleevestill vbeing open. :Eaccordirlg'ly., .the first opening and .reclosing .of the circuit vbreaker contacts will "both occur .substantially `instantaneously with .no vtime delay interposed `due to 'the dashpot .ao-'tion of c ore 7.3 jin dashpot vsleeve i. During reelosing .of the @breaker gthe .rst time, .integrating piston '13e .-is left at z.the vposition `to which it was advanced, .since jpawl member lfii iis Tree :to vclisengage vthe .circular flanges .I fiil, and if the Abreaker zreraains closed, integrator vpiston l-S will slowly reset to the @position shown :Fig :1, vthis resetting :move- Vanent fbeing flrelatively zslow .due 'to the `necessity v* during the opening operation, past the relatively small clearance between cylinder |30 and piston |36. This means, of course, that if an overload appears on the circuit at a later time, the breaker contacts will then be substantially instantaneously opened and closed in the manner described above.

Inasmuch as the initial circuit-opening and followingr circuit-closing operations are not restrained in any manner by the dashpot comprising core and sleeves 14 and 82, these operations may occur so rapidly on relatively high overloads that the counting mechanism either does not operate or operates improperly. In order to overcome this, momentary time delay is imposed due to piston iiange 8l of core 16 entering the cylindrical skirt 85 on sleeve 10, to provide a very short dashpot delaying action. This has been found suiiicient to provide for proper operation of the various parts of the breaker, and, at the same time, does not materially add to the reclosingtime on low overloads.

If the breaker immediately reopens after a rst opening and reclosing operation, pawl member |54 this time will engage the next lower circular iiange |40 on the integrator cylinder |30, so that the integrator piston acts as a valve to close off the vent passage |14 from the upper end of dashpot cylinder 14. inasmuch as the integrator piston |36 does not close the vent passage until bridging contact 35 is substantially at the end of its circuit-opening movement, this second closely successive circuit-opening operation will, like the iirst, occur substantially instantaneously with substantially no delay due to dashpot cylinder 14 and core 16. However, on the succeeding reclosing operation, integrator piston |30 having closed the vent at the top oi dashpot cylinder 14, this reclosing operation will be delayed throughout in the manner previously described by the dashpot action of core 15 in cylinder 14. This second reclosing operation will result in leaving piston i3d at the further advanced position described above, from which it eventually will reset in the manner previously described if the breaker remains closed, so that an overload appearing on the circuit at a later time will result in the breaker operating in the manner described above for the iirst and second closely succeeding circuit-opening and closing operations. However, in the event the overload continues after the second closely succeeding circuit-opening and closing operations, the breaker will again open, and this time the opening operation will be delayed by the dashpot action of core 16 in dashpot sleeve 14, since integrator piston |35 has not had time to recede from the position to which it was advanced on the second opening operation of this series of closely succeeding circuit-opening operations, where it blocks the vent passage from the upper end of dashpot sleeeve 14.

The circuit-closing operation of the breaker following the third opening will be delayed in the manner previously described, inasmuch as such third opening operation results in further advance of integrator piston |36 where it still blocks the vent passageway from the upper end of dashpot sleeve 14. The breaker may then continue to open and reclose if the overload continues, with each opening and closing being delayed by the dashpot action of core 10 in dashpot sleeve 14, until nally pawl member |54 advances integrator piston 36 an amount sufficient to cause theupper extension |42 thereof to engage eX- tension |43 of toggle lever |04, and move this lever upwardly overcenterso that toggle spring |24 will maintain the contacts separated in the manner previously described. It is thus apparent that toggle levers |04 and lili will be automatically moved upwardly overcenter to maintain the breaker contacts separated only in response to a predetermined number of closely successive circuit-opening and closing operations, usually four such operations; however, in the event a lesser number of closely successive opening and closing operations occurs, the integrating mechanism will reset, and the breaker contacts will be automatically held open only when the aforesaid predetermined number oi opening and closing operations occurs in close succession. Obviously, after the breaker contacts have been automatically actuated to a position where they are held open by toggle spring |24, they can be reclosed only by manual operation of toggle lever |I4 in the manner previously described.

In the preferred sequence of operations leading to the breaker contacts being maintained in open circuit position mentioned above, that is, a sequence of four operations, it will be apparent that with the apparatus described above, the iirst two opening operations will occur substantially instantaneously and the second two opening operations will be delayed with an inverse time-current characteristic due to the dashpot action of core 16 in dashpot sleeve 14. Moreover, the reclosing times in any such sequence of four closely successive opening and closing operations will comprise a rst substantially instantaneous closing operation, with but a momentary delay, with the remaining circuit-closing operations being delayed throughout by the dashpot action of core 16 in dashpot sleeve 14.

Ii desired, a protective gap device |66 of the expulsion type may be provided to prevent operation of the breaker on voltage surges, with the outer tube of the protective device mounted intermediate its ends on an extension |68 of supporting plate 22 at the underside of solenoid coil 24, being secured thereto, as by nuts |10, threaded on the tube of the protector device. One terminal |12 of the protective device may be connected with conductor |00 and one side of solenoid coil 24, with the other terminal of the protective device (not shown) connected with the other terminal of coil 24 and conductor |02. This arrester and its particular manner of mounting and connection with this type of apparatus is more particularly disclosed and claimed in the copending application of H. L. Rawlins and J. M. Wallace, Serial No. 694,074 on Overvoltage Protective Devices, iiled August 3D, 1946, now U. S. Patent 2,550,124, issued April 24, 1951, and assigned to the same assignee of this invention. As stated above, the purpose of providing a protective device i connected in the manner described herein and in the aforesaid copending application is to provide a by-pass for solenoid coil 24 on voltage surges such, for example, as those due to lightning strokes, which are not overloads on the circuit, and, consequently, it is not desired that the breaker open on such surges.

My invention is particularly concerned with the arc-extinguishing chamber |1|, which is substantially enclosed to provide more eective arc-extinguishing action by utilizing a bottom or end plate |82 of any suitable insulating material, as more particularly shown in Figures l and 3. Referring to Figure 3, it will be noted that the end plate |82 has a pair of cutout portions H3 provided therein, which serve to space the stationary contacts 2S from the side edges disposed cutout portions adjacent the stationary contacts so that a gap distance in liquid exists between each stationary contact and the end plate to minimize insulation breakdown between the stationary contacts when the interrupter is in the open circuit position.

4. A circuit interrupter including an arc extinguishing chamber comprising a tubular member, a pair of stationary contacts supported adjacent the side walls of the tubular member, a pair of movable contacts separable away from the stationary contacts to establish a pair of arcs within the tubular member, a relatively stationary end plate of insulating` material partially enclosing one end or" the tubular member and having a cutout portion for each stationary contact, each cutout portion spacing the end plate away from the respective stationary contact by a gap distance to minimize insulation breakdown between the stationary contacts when the interrupter is in the` open circuit position, and a pair of slots in the side walls of the tubular member for each stationary contact, on opposite sides thereof, to lengthen the creepage path between the stationary contacts.

A circuit interrupter of the liquid break type including an arc extinguishing chamber immersed in an arc extinguishing liquid comprising a tubular member, a pair of stationary contacts supported on the side walls of the tubular member, a pair oi' movable contacts separable away from the stationary contacts to establish a pair of arcs within the vtubular member, a relatively stationary end plate of insulating material partially enclosing one end of the tubular member and having a cutout portion for each stationary contact, each cutout portion spacing the end plate away from the respective stationary contact by a gap distance in liquid to minimize insulation breakdown. between the stationary contacts when the interrupter is in the open circuit position, and a pair of slots in the side walls of the tubular member for each stationary contact, on opposite sides thereof, to lengthen the creepage path between the stationary contacts.

6. The combination in a liquid. break circuit interrupter of a pair of stationary contacts mounted diametrically on opposite sides of a cylindrical member, a conducting bridging member electrically interconnecting the two stationary contacts in the closed circuit position, a relatively stationary end plate of insulating material partially enclosing one end of the cylindrical member and having a pair of diametrically disposed cutout portions adjacent the stationary contacts so that a gap distance in liquid exists between each stationary contact and the end plate to minimize insulation breakdown between the stationary contacts when the interrupter is in the open circuit position, and a pair of slots in the side walls of the cylindrical member for each stationary contact, on opposite sides thereof, to lengthen the creepage path between the stationary contacts.

7. An automatic reclosing circuit breaker comprising a liquid container, an arc extinguishing chamber positioned in said container below the liquid level thereof and including a tubular member, a pair of stationary contacts supported adjacent the side walls oi the tubular member, a pair of cooperable movable contacts separable from the stationary contacts to establish a pair of arcs within the tubular member, overloadresponsive means for moving the movable contacts to open the circuit, the movable contacts being biased to engage the stationary contacts to automatically reclose the circuit following a circuit interrupting operation, and a relatively stationary end plate of insulating material partially enclosing one end of the tubular member and having a cutout portion for each stationary contact, each cutout portion spacing the end plate away from the respective stationary contact by a gap distance to minimize insulation breakdown between the stationary contacts when the interrupter is in the open circuit position.

8. An automatic reclosing circuit breaker comprising a liquid container, an arc extinguishing chamber positioned in said container below the liquid level thereof and including a tubular member, a pair of stationary contacts supported adjacent the side walls of the tubular member, a pair of cooperable movable contacts separable from the stationary contacts to establish a pair of arcs within the tubular member, overloadresponsive means for moving the movable contacts to open the circuit, the movable contacts being biased to engage the stationary contacts to automatically reclose the circuit following a circuit interrupting operation, and a relatively stationary end plate of insulating material partially enclosing one end of the tubular member and having a cutout portion for each stationary contact, each cutout portion spacing the end plate away from the respective stationary contact by a gap distance to minimize insulation breakdown between the stationary contacts when the interrupter is in the open circuit position, and a pair of slots in the side walls of the tubular member for each stationary contact, on opposite sides thereof, to lengthen the creepage path between the stationary contacts.

9. An automatic reclosing circuit breaker comprising a liquid container, an arc extinguishing chamber positioned in said container below the liquid level thereof and including a cylindrical member, a pair of stationary contacts mounted diametrically on opposite sides of the cylindrical member, a conducting bridging member electrically interconnecting the two stationary contacts in the closed circuit position, overload-responsive means for moving the bridging member to open the circuit, the bridging member being biased to engage the stationary contacts to automatically reclose the circuit following a circuit interrupting operation, and a relatively stationary end plate of insulating material partially enclosing one end of the cylindrical member and having a pair of diametrically disposed cutout portions adjacent the stationary contacts so that a gap distance in liquid exists between each stationary contact and the end plate to minimize insulation breakdown between the stationary contacts when the interrupter is in the open circuit position.

10. An automatic reclosing circuit breaker comprising a liquid container, an arc extinguishing chamber positioned in said container below the liquid level thereof and including a cylindrical member, a pair of stationary contacts mounted diametrically on opposite sides of the cylindrical member, a conducting bridging member electrically interconnecting the two stationary contacts in the closed circuit position, overload-responsive means for moving the bridging member to open the circuit, the bridging member being biased to engage the stationary contacts to automatically reclose the circuit following a circuit interrupting operation, a relatively' stationaryt end: plate: of; insulatingr material;r

partially' enclosing, one. end ot the cylindrical member and having a pair of diarnetrica-llyr dis-y posediL cutout portions adjacentv the. stationary contacts sov that a gapr distance. ini liquid existsV the; stationary contacts when. the interruptorY is.

inthe open circuit position, and a pair of slots inf, the. side walls of the cylindrical member for each` stationary contact, onV opposite sidesthereoff.. to lengthen, the creepage path between the stationary contacts.

ll. circuit. interruptor including means devented arc-extinguishing chamber', said er having a side-Wall; portion, a relatively stationary` contact mounted on, the side-wall-portion.. a movable contact cooperable withthefrelatively stations y contactto establish anarc, a sta-- tionary plate of insulating material extending at least part way across. the` Varc-extinguislf-iing chamber having. a cutout portion to accom.- modate the stationary contact, and said cut out portion providingr a space between the plateand the relatively stationary Contact to provide a gap distance therecet.veeny to minimize insulation breal'rdown across surface of the platewhenthe: interrupt r is inthe open circuit position.

12....fr circuit interruptor of the liquid-break type including means defining' a vented arc-extinguishingV chamber immersed in an arc-eX- tinguishing liquid, said chamber having a sidewall portion,A a relatively stationary contact mountedY on the side-wall portion, a movable'contact cooperable'with the relatively stationarycontact to establish an arc, a plate of insulating material extending at least part way across the arcextinguishing chamber, and a space'between the plateanz the relatively stationary contact to provide a gap-distance in liquid therebetween to minimiseinsuiation breakdown across the surface of, the plate when the interruptorV is in the open circuit position.

1-3. A circuit interruptor including means-denna vented. arc-extinguishing chamber, said chamber having a side-Wall portion, a relatively stationary contact mounted, on the side-wall portion,v a movable Contact cooperable with the relatively stationary contact to establish an arc, a

stationary plate or" insulating material eXtending; f

at least part Way across the arc-extinguishing chamber, a space between the plate andthe relatively stationary contact to provide a gap distance therebetween to minimize insulation breakdown across the surface of t -e plate when the interis inv the open circuit position, a pair of spaced slots in the side-wall portion on opposite sides of the stationary Contact, and the stationary contact being mounted between the spaced slots toy the side wa-ll portion to; thereby,- lengthenV the. creepagepath between the stationary contact and. conducting parts ofa different potential..

14.. A circuit interrupter of the liquid-break type incliuiingv means denn-ing a vented arc-extinguish ing chamber immersed in an arc-extinguishing. liquid, said chamber having a side-walll portion, a relativelyA stationary contact mounted onl the. side-wall portion, a movable contact cooperable; with the relatively stationary contact to establish anA arc, a plate of insulating material extending at least part way across the arc-extinguishing chamber,` a space between the plate and the,l rela,- tively stationary contact to provide a gap distance,- in liquidl therebetween to minimize; insulation breakdownY across the surface ofthe platevvhen the interruptor is in, the open circuit position, anda pair of slots inthe side-wall portion on opposite sides. of the stationary contact to lengthen: theA creepage path between the stationary contact and' conducting parts of a different potential.

15. A circuit interrupter including means defining; a ventedarc-extinguishing chamber, said chamber having a side-wall portion, a rela-tively stationary contact mounted on the side-Walliportion, a movable contactv cooperable with the relatively stationary Contact to establish an. are, a plate of insulating material'extending at least part way across the arc-extinguishing chamber,i apair of spaced slots in the side-wall portion onopposite sidesof the stationary contact, and thel stationary contact being mounted between the spaced slots to the side Wall portion to' therebyV lengthenthe creepage path between the stationary contactv and conducting parts of a diierent potential.,

16. A circuit interruptor ofthe liquid-breaktype ineluding'means defining a vented arc-extinguishing chamber immersed in an arc-extinguishing liquid, said chamber having a side-wall portion, a relatively stationary contact mounted on the sidewall portion, a movable contact cooperable with the relatively stationary contact to establishy an arc, a plate of insulating material extending at least part way across the arc-extinguishing chamber, and a pair of slots in the side-Wall portion on opposite sides of the stationary contact, to lengthen the creepage path between the: stationaryv contact and conducting parts of a different potential.

ALERT M. OPSAHL.

References Cited in theVV file of this patent UNITED STATES PATENTS Number Name D ate 1,895,330 Kempton,V Jan. 24, 1933 2,365,502 Slepian Dec. 191944 2,442,477 Wallace et al. June 1,V 1948 2,518,195 Skeats Aug; 8, 1950 

